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Flame retardant materials: Buying you time

23rd Oct 2007 , Dan Daniel; Acti-Chem

Did you know… The main hazards in a fire are the toxic products of combustion, especially in confined spaces such as buildings, vehicles, etc.

Which overall would you rather be wearing? A flame-retardant overall doesn't guarantee that you won't burn – if you were wearing the overall on the left you would have had time to take it off and escape with minor burns.

A flame-retardant overall will buy you time – if you were wearing the overall on the right you may not have the time to undress.

Use a natural fibre – for flame-retardant overalls durable to repeated washing, cotton is your best bet. Synthetics can be made flame-retardant, but are prone to melting and shrinking which can cause as much damage as flames.

Test method – the South African test method normally used is SABS 1423 Part 1 of 1987. In addition it is normal to specify the number and type of wash cycles the overall must stand up to and remain flame-retardant.

Wash fastness – a flame-retardant cotton overall should last for a year. Assuming it will be washed once a week, it should be durable to at least 50 washes at 60ºC using an industrial detergent.

Textiles, upholstery and furnishings are the materials or items that are mainly responsible for the development of fire.

Did you know…

The main hazards in a fire are the toxic products of combustion, especially in confined spaces such as buildings, vehicles, etc. Fire is always associated with toxic fume evolution and the effect on the human respiratory system. Not only can toxic fumes incapacitate or kill in the vicinity of the fire but they can rapidly spread to other areas. It is therefore very important that the textiles and other materials be assessed in terms of their propensity to emit products of combustion. In the table below the most common toxic species and their effects on humans have been listed.

All fires cause oxygen depletion in their immediate vicinities. Death occurs if the oxygen content drops below 6% by volume (normal air contains 21%). All fires, especially smouldering fires, produce carbon monoxide which can kill within minutes if the concentration exceeds 5,000 ppm. All fires produce carbon dioxide. This is the main product of combustion and is an asphyxiant.Textile fibres which contain nitrogen, such as nylon, wool and modacrylics as well as polyurethane foam in cushioning, will produce volatile cyanide compounds to a lesser or greater degree. As little as 180 ppm of these in the atmosphere will cause death within 10 minutes.

Toxic species, such as hydrogen chloride from PVC coatings, and Acrolein from cellulosic fibres can also evolve. Further, antimony compounds which are used in conjunction with halogens (chlorine or bromine) to confer flame retardant properties in textile fibres and coatings can cause short and long term effects on the body.

The chemical effects of fire - which materials produce what:

PRODUCT SOURCE EFFECT
Oxygen depletion All fires 12-15% - Headache, dizziness
<6% - Death in 6-8 minutes
Carbon Monoxide All fires, materials containing carbon 2000 ppm – Death after 45 minutes
5000 ppm – Death within 5 minutes
Carbon Dioxide All fires, materials containing carbon 5% - Headache, dizziness, nausea
7-10% - Death within 5 minutes
Hydrogen Cyanide Nylon, silk etc 180 ppm – Death after 10 minutes
300 ppm – Immediately fatal
Hydrogen Chloride Polyvinyl Chloride etc 2000 ppm – Death within 5 minutes
Hydrogen Bromide FR products 500 ppm – Death after 10 minutes
Hydrogen Sulphide Wool 1000 ppm – Death in less than 1 hour
Acrolein Cellulosics (cotton) 1 ppm – Severe irritation
150 ppm – Death in 10 minutes
Ammonia Nitrogen containing formulations 2000 ppm – Death in less than 1 hour
Antimony Halogen FR FR Back-coating products Gastric problems and possibly carcinogenic
     

 

 

 

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